Canvas button

ABSTRACT

A two-piece canvas button comprises a shell, a back, and a piece of artist canvas tightly tucked between the shell and back. The shell provides a sturdy mounting for the artist canvas, on which an artist paints. The back may be a formed back with a frusto-conical margin that cooperates with a frusto-conical wall of the shell to tightly tuck the artist canvas. Alternately, the back may be a flat back, in which case the artist canvas is tightly tucked between the periphery of the flat back and the shell frusto-conical wall. A round canvas button with the flat back may have a flat coplanar flange; the artist canvas is tightly tucked between the flange and the back. A rectangular canvas button has coplanar flanges. Machines for manufacturing the canvas buttons may use either a third press stroke or only two strokes to manufacture the buttons with the coplanar flanges.

RELATED APPLICATION

This application is a continuation of co-pending U.S. patent application Ser. No. 10/414,330, filed 16 Apr. 2003.

FIELD OF THE INVENTION

This invention pertains to artist supplies, and more particularly to supplies used for fine art painting.

DESCRIPTION OF THE PRIOR ART

Artist canvas is well known and has been in widespread use for many years. Typically, a piece of artist canvas is stretched over and fastened to a working frame. The canvas is then ready to receive any of a variety of color patterns applied to it by the artist.

A problem with prior working frames and artist canvas was the lack of support for the center area of the canvas. Even if the artist canvas was stretched tightly across the working frame, the center area tended to deflect under the force of a brush as the paint was applied. Besides being a nuisance, the deflected canvas had a deleterious effect on the accuracy of the placement of the paint, and the artist had to compensate for the deflection as he applied paint to the canvas.

A further limitation concerning prior paintings was that they usually required a second frame to hold them for display. The cost of a display frame plus the labor involved in the framing process often approached or even exceeded the value of the painting itself. The limitations associated with framing paintings for display was especially acute when the paintings were small, such as a few inches square. The display frames for such small paintings tended to dominate the paintings.

To avoid the difficulties associated with display frames, prior paintings were sometimes left on the original working frames for display. That method of displaying paintings was less attractive than desireable.

The Lar Lu company distributes buttons under the trademark LarLuLine that are capable of being written on with crayons or felt markers. The prior Lar Lu buttons are of one-piece construction, as that term is used in the button art. One-piece buttons have only a domed shell and a graphic laid over the shell. The graphic is captured between a flange of the shell that is bent over at 180 degrees to overlie the graphic margin and the margin of the shell adjacent the flange. In the prior Lar Lu buttons, the graphic is a piece of oilcloth or the like. The Lar Lu buttons are not designed to receive artist's paint, nor do they possess the quality of buttons with two-piece construction.

Thus, a need exists for improvements in media for fine art paintings.

SUMMARY OF THE INVENTION

In accordance with the present invention, a two-piece button provides a new medium for fine art painting without expectation of replacing any current media such as plastic film, paper, masonite, or metal. This is accomplished by incorporating blank artist canvas into round or rectangular buttons. The present invention further contemplates incorporating pre-painted artist canvas, as well as artist canvas that is pre-printed by computer reproduction, into round and rectangular buttons.

An exemplary machine for assembling round canvas buttons is shown in my U.S. Pat. No. 6,038,944, the specification and drawings of which are incorporated herein by reference. To assemble a round canvas button with a formed back using the universal assembly machine of the U.S. Pat. No. 6,038,944 patent, a handle is initially pivoted to a ready position. In that position, a ram spring biases a ram away from a die table. A round shell with an annular margin is placed dome upward on a pedestal of a pickup die. A circular piece of artist canvas is placed above the shell in a pickup die outer frame. The die table is indexed to place the pickup die under the ram. Doing so causes an actuator to shift the ram to a pickup mode such that ram pins are not aligned with corresponding holes in the ram.

The handle is pivoted in a pickup stroke. Doing so advances the ram downwardly toward the pickup die. The ram, acting through the ram pins, forces the pickup die outer frame downwardly against a spring force. Simultaneously, the ram bends the artist canvas to conform to the shape of the shell. At the end of the pickup stroke, the artist canvas is fully formed over the shell. There is a skirt of the artist canvas overhanging the free edge of the shell margin. Reverse pivoting of the handle back to the ready position enables the ram to retract, with the shell and artist canvas held by friction in the ram.

A formed back with a frusto-conical margin is placed on a pedestal of a crimp die. The die table is then indexed to position the crimp die under the ram. Rotating the die table causes the actuator to switch the ram to a crimp mode such that the ram pins become aligned with the corresponding ram holes. Pivoting the handle advances the ram in a crimp stroke. The artist canvas and shell advance toward the formed back. Advancing the ram first causes the artist canvas skirt to bend over the free edge of the shell margin and to tuck between the shell margin and the periphery of the back. Continued pivoting of the handle bends the shell margin into a frusto-conical wall and tightly tucks the artist canvas between shell frusto-conical wall and the back periphery. Upon reverse pivoting of the handle, the ram retracts to expose the assembled round canvas button.

The present invention further includes round canvas buttons having flat backs. The same machine components and operations may be used as described previously with but one exception. Because of the difference in height between the formed back with the frusto-conical margin and a flat back, a different crimp die pedestal is required. Alternately, the same crimp die pedestal can be used with an adapter that compensates for the different heights of the formed and flat backs. Whether or not the adapter is used, the skirt of the artist canvas of the completed button is tightly tucked between the flat back periphery and the shell frusto-conical wall.

Another important feature of the present invention is a round canvas button with a single planar flange. The round canvas button with the planar flange is composed of an artist canvas, a shell, and a flat back. The manufacturing process for the round canvas button with a planar flange begins with the manufacture of a round canvas button with a flat back. After the crimp stroke, the flat back canvas button is transferred to the pickup die. The die table is again indexed to position the pickup die under the ram. The ram is advanced in a third press stroke in which a ram plug contacts the outer edge of the flat back canvas button and forces the shell frusto-conical wall against the pickup die pedestal. The result is that the shell frusto-conical wall bends inwardly over and against the flat back and to form a flange that lies in a single flat plane.

According to another aspect of the invention, the canvas button is rectangular in shape. The rectangular canvas button is comprised of a rectangular shell, flat back, and piece of artist canvas. The rectangular canvas button may be manufactured according to the teachings of my co-pending U.S. patent application Ser. No. 10/342,064 filed Jan. 14, 2003. The machine described in U.S. patent application Ser. No. 10/342,064 manufactures rectangular canvas buttons in a two-stroke operation. The shell of the rectangular canvas button has coplanar flanges. The general construction and operation of the machine of U.S. patent application Ser. No. 10/342,064 is generally similar to the machine of the U.S. Pat. No. 6,038,944 patent. However, the third press stroke of the machine of the U.S. Pat. No. 6,038,944 patent is eliminated; only two strokes are required when using the machine of U.S. patent application Ser. No. 10/342,064.

The machine of U.S. patent application Ser. No. 10/342,064 is also capable of manufacturing round canvas buttons with flat backs and planar flanges in a two-stroke operation. Thus, the round canvas button with the flat back and planar flange may be manufactured by either the machine of the U.S. Pat. No. 6,038,944 patent or the machine of U.S. patent application Ser. No. 10/342,064.

The method and apparatus of the invention, using artist canvas, thus provides a new medium on which an artist can paint, as well as a means of displaying artist canvas that is pre-painted or pre-printed. The canvas button has a sturdy surface that supports the entire artist canvas, and buttons are no longer limited to use with reproduction graphics.

Other advantages, benefits, and features of the present invention will become apparent to those skilled in the art upon reading the detailed description of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a round canvas button with a formed back according to the present invention.

FIG. 1A is a partial cross sectional view of the round canvas button shown in a partially assembled condition.

FIG. 1B is a partial cross sectional view of the round canvas button of FIG. 1A, but showing the button in the fully assembled condition.

FIG. 2 is a view similar to FIG. 1B, but showing a round canvas button made with a collet.

FIG. 3 is a broken cross sectional view taken along line 3-3 of FIG. 4 showing a universal assembly machine with the crimp die under the ram and the ram retracted.

FIG. 4 is a view taken along line 4-4 of FIG. 3.

FIG. 5 is a view taken along line 5-5 of FIG. 3.

FIG. 6 is a broken cross sectional view taken along line 6-6 of FIG. 7 and showing the pickup die under the ram and the ram advanced in a pickup stroke.

FIG. 7 is a view taken along line 7-7 of FIG. 6.

FIG. 8 is a broken cross-sectional view generally similar to FIG. 6, but showing the crimp die under the ram.

FIGS. 9A-9C are cross sectional views through the ram and the pickup die showing the pickup function of the universal assembly machine.

FIGS. 10A-10C are cross sectional views through the ram and the crimp die showing the crimp function on a button with a formed back.

FIG. 11 is an exploded perspective view of a round canvas button made with a flat back in accordance with the present invention.

FIG. 11A is a cross sectional view of the assembled round canvas button with a flat back according to the present invention.

FIGS. 12A-12C are cross sectional views through the ram and a modified crimp die used to manufacture the round canvas button with the flat back of FIGS. 11 and 11A.

FIG. 13 is an exploded perspective view of a round canvas button with a coplanar flange according to the present invention.

FIG. 13A is a cross sectional view on an enlarged scale of an assembled round canvas button with a coplanar flange according to the invention.

FIGS. 14A-14C are cross sectional views through the ram and the pickup die showing the third press stroke used during the manufacture of the round canvas button with a coplanar flange of FIGS. 13 and 13A.

FIG. 15 is a cross sectional view through the crimp die pedestal used to manufacture round canvas buttons with formed backs and adapted to also be capable of manufacturing round canvas buttons with flat backs and coplanar flanges.

FIG. 15A is a view similar to FIG. 15, but showing a modified adapter.

FIG. 16 is a top perspective view of a rectangular canvas button with coplanar shell flanges.

FIG. 16A is a bottom perspective view of the rectangular canvas button of FIG. 16.

FIG. 17 is an exploded view of the components of the rectangular canvas button of FIG. 16.

FIG. 18 is a partial cross-sectional view of the rectangular canvas button of FIG. 16.

FIG. 19 is a cross-sectional view taken along line 19-19 of FIG. 20 showing a machine capable of manufacturing the rectangular canvas buttons having coplanar flanges of the invention.

FIG. 20 is a view taken along line 20-20 of FIG. 19.

FIG. 21 is a view taken along line 21-21 of FIG. 19.

FIG. 22 is a view taken along line 22-22 of FIG. 19.

FIG. 23 is a broken cross-sectional view taken along line 23-23 of FIG. 24 showing the pickup die under the ram and the ram advanced in a pickup stroke.

FIG. 24 is a view taken along line 24-24 of FIG. 23.

FIG. 25 is a partial cross-sectional view generally similar to FIG. 19 but showing the machine at the start of the crimp stroke.

FIGS. 26A-26E show the action of the ram die and crimp die during the crimp stroke.

FIG. 27 is a partially broken view generally similar to FIG. 25, but showing the machine at the end of the crimp stroke.

FIG. 28 is a cross-sectional view taken along line 28-28 of FIG. 29 of a machine for manufacturing round canvas buttons with coplanar shell flanges according to the present invention.

FIG. 29 is a view taken along line 29-29 of FIG. 28.

FIG. 30 is a cross-sectional view of the machine of FIGS. 28 and 29 at the end of the pickup stroke and taken along line 30-30 of FIG. 31.

FIG. 31 is a view taken along line 31-31 of FIG. 30.

FIG. 32 is a cross-sectional view of the machine of FIGS. 28-31 at the end of the crimp stroke.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Although the disclosure hereof is detailed and exact to enable those skilled in the art to practice the invention, the physical embodiments herein disclosed merely exemplify the invention, which may be embodied in other specific structure. The scope of the invention is defined in the claims appended hereto.

Round Canvas Button

Referring first to FIGS. 1, 1A, and 1B, a round two-piece canvas button 1 is illustrated that includes the present invention. The canvas button 1 is comprised of a piece of blank artist canvas 3, a round shell 7, and a formed back 9. However, it will be understood that the invention is not limited to original painting applications. For example, the artist canvas may be pre-painted, or pre-printed with computer generated and printed artwork or with reproductions of artists' originals. For all uses, the artist canvas presents a very realistic and attractive appearance of the art displayed on it.

The shell 7 is preferably made of thin gauge sheet steel. It has a center region in the form of a dome 6 and a free edge 13. There is a margin 5 adjacent the free edge 13. For the round shell 7, the margin 5 is in the shape of an annular wall 8. The dome 6 is a convex presentation surface that can vary in height from some maximum to zero, in which case the center region would be flat. Although the shell is shown and will be described as being round, oval shells are also within the scope of the present invention.

A circular piece of artist canvas 3 is overlaid on the shell dome 6 and surrounds the shell wall 8. The artist canvas 3 may be sized or primed for use with any artist medium. A suitable artist canvas is marketed under the trademark Fredrix. The artist canvas has a skirt portion 11 that overhangs the free edge 13 of the shell wall 8.

The formed back 9, which is also usually made of steel, has a center region 10 surrounded by a margin 21. For the formed back 9, the margin 21 includes an inner frusto-conical wall 12. The inner frusto-conical wall 12 joins at a smooth junction 14 to an outer reverse frusto-conical wall 15. The outer frusto-conical wall 15 defines a periphery 16 of the margin 21. The periphery 16 may be approximately in the same plane as the center region 10. The formed back center region is close to and parallel to the shell dome 6.

As will be explained in detail shortly, the artist canvas 3, shell 7, and formed back 9 are assembled into the completed round canvas button 1 by tucking the skirt 11 of the artist canvas around the free edge 13 of the shell wall 8. The skirt is laid over the periphery 16 of the formed back margin 21. Then the shell wall is crimped against the outer frusto-conical wall 15 of the formed back. The shell wall becomes frusto-conical in shape, as is indicated at reference numeral 8A in FIG. 1B, and the artist canvas is tightly tucked between the shell wall 8A and the formed back outer frusto conical wall 15.

Also looking at FIG. 2, a canvas button 18 is similar to the canvas button h described previously with regard to FIGS. 1, 1A, and 1B. The canvas button 18 has a piece of artist canvas 3′ and a domed shell 7′. Instead of a formed back, however, the canvas button 18 is made with a collet 20. The collet 20 has a center region that is an opening 24 surrounded by a margin 22. As illustrated, the margin 22 comprises a short inner frusto-conical wall 23. An outer frusto-conical wall 25 joins to the inner frusto-conical wall 23 at a junction 27.

Assembly Machine

Turning to FIGS. 3, 4, and 5, a universal assembly machine 33 is illustrated that is useful for economically manufacturing the round canvas buttons 1 as shown in FIGS. 1, 1A, 1B, and 2. However, as will be explained in detail later, the assembly machine 33 is also capable of manufacturing additional products.

The universal assembly machine 33 is comprised of a box framework 34 that includes an elongated base 35. Upstanding from the base 35 is a center column 37 and a similar end column 39. Spanning the center column and the end column 39 is a crown 41.

Pivotally connected to the crown 41 is a handle 45. In the illustrated construction, the handle 45 has a pair of plates 47 that straddle the crown and are pivotally connected to it by a pin 49. The plates 47 terminate in a hand grip 51. The plates have respective cam surfaces 53 opposite the grip 51. As shown in FIG. 3, the handle is in a ready position.

A ram 59 is supported and guided by the crown 41 for reciprocating along a vertical axis 61. The ram 59 includes a carrier 63 and a ram die 64. The carrier 63 is biased toward the crown by a spring 69 acting between the head 71 of a screw 65 and a recess in the crown. There are a pair of holes 68 in the carrier diametrically opposite the axis 61. A pair of rollers 66 extend oppositely from the sides 62 of the carrier. When the handle 45 is in the ready position of FIG. 3, the handle cam surfaces are in close proximity to the rollers 66, but the handle cam surfaces do not exert any force on the rollers.

The ram die 64 is comprised of a cylindrical plug 73 and a ram frame 85. A working face 75 of the plug 73 is concave so as to define a cavity 77 having a tapered annular surface 81. As illustrated, the tapered annular surface 81 is flat. However, to better suit some canvas buttons 1 or 18, a scalloped or curved surface can be used instead of a flat surface. There is an external shoulder 83 on the plug.

The ram frame 85 is slideable and rotatable over the outer diameter of the plug 73. The ram frame 85 has an internal diameter 86 and an internal shoulder that normally rests on the plug external shoulder 83 under the force of gravity. A pair of pins 87 are pressed into the ram frame at the same radial distance from the axis 61 as the holes 68 in the carrier 63. A pair of fingers 89 and 91 jut outwardly from the ram frame. The fingers 89 and 91 are preferably parallel to each other and are on opposite sides of a transverse axis 96 through the vertical centerline 61. The lower end of the ram frame has an end surface 93 with a tapered pilot 95.

Rotatably supported on the framework base 35 is a die table 97. The die table 97 is indexable through 180 degrees about the center column 37. A vertical shifter post 103 is joined to the die table. The shifter post is long enough to reach the fingers 89 and 91.

Mounted to opposite ends of the die table 97 are a pickup die 109 and a crimp die 111. The pickup die 109 comprises a cylindrical pedestal 113 having an external shoulder 115 and a top surface 117. An outer frame 119 with an inner diameter 120 is slideable over the pedestal 113. Springs 121 bias an internal shoulder of the outer frame 119 against the pedestal external shoulder 115. The outer frame has a recess 123 in the upper surface 125 thereof.

The crimp die 111 has a pedestal 127 with an external shoulder 129, an outer diameter 130, and an upper surface 131 with a recess 133. A crimp die outer frame 135 is biased by springs 137 such that an internal shoulder 138 abuts the pedestal external shoulder 129. An upper surface 139 of the outer frame 135 has a recess 141 and a bevel 143. The bevel 143 is shown as being flat. However, like the tapered surface 81 in the ram plug 73, the bevel 143 can be scalloped or curved to suit the particular canvas button 1 or 18 to be assembled.

Operation

The operation of the universal assembly machine 33 to manufacture a canvas button 1 begins by placing a shell 7 dome side up on the pedestal 113 of the pickup die 109. See FIG. 9A. The artist canvas 3 is placed in the recess 123 of the pickup die outer frame 119. The machine die table 97 is indexed in the direction of arrow 145 such that the pickup die is under the ram 59, FIG. 4. As the die table indexes in the direction of arrow 145, the shifter post 103 also travels in a semi-circle to its position shown in FIG. 7. The circular travel of the shifter post causes it to contact the finger 91 and rotate the ram frame 85 on the ram plug 73 in the direction of arrow 147 to a pickup mode. When the ram frame is in the pickup mode of FIG. 7, the pins 87 in the ram frame are misaligned with the holes 68 in the carrier 63.

The handle 45 is pivoted clockwise with respect to FIGS. 3 and 6 in a pickup stroke toward a generally horizontal working position. The handle cam surfaces 53 contact the rollers 66 and force the carrier 63 downwardly against the spring 69. The ram 59 advances to bring the end surface 93 of the ram frame 85 into contact with the artist canvas 3. A slight further pivoting of the handle advances the ram plug 73, but not the ram frame, through the clearance C. Advancement of the ram frame is resisted at that time by the springs 121 acting through the pickup die outer frame 119. Further advancement of the ram causes the carrier to contact the pins 87 and then advance the ram frame to force the pickup die outer frame against the springs 121 and form the artist canvas over the shell 7, FIG. 9B. A wrinkled skirt 11 of the artist canvas overhangs the shell free edge 13. Simultaneously, the artist canvas and shell slide into the inner diameter 86 of the ram frame.

When the handle is pivoted back to the ready position of FIG. 3, the spring 69 retracts the ram 59 away from the pickup die 109, FIG. 9C. At the end of the pickup stroke, the shell 7 and artist canvas 3 are held by friction in the inner diameter 86 of the ram frame 85.

A formed back 9 is placed in the crimp die 111 with the junction 14 resting on the pedestal 127. See FIG. 127. The die table 97 is then indexed 180 degrees in the direction of arrow 151, FIG. 7. Indexing the die table causes the shifter post 103 to travel in an arcuate path in the direction of arrow 151. The shifter post contacts the finger 89 in the ram frame 85. The shifter post acts against the finger 89 to rotate the ram frame in the direction of arrow 153 to a crimp mode as shown in FIG. 4. When the ram frame is in the crimp mode, the pins 87 are aligned with the holes 68 in the carrier 63, the finger 89 is proximate the shifter post, and the finger 91 is proximate the center column 37.

The handle 45 is pivoted clockwise (with respect to FIG. 3) in a crimp stroke. See FIGS. 10A-10C. The carrier 63 advances until the ram frame 85 contacts the crimp die outer frame 135. Further pivoting of the handle causes the ram plug 73 to advance, but the springs 137, acting through the crimp die outer frame 135, prevent advancement of the ram frame 85. The pins 87 in the ram frame enter the holes 68 in the carrier 63. The ram plug 73 thus advances without corresponding advancement of the ram frame. The ram plug advances to push the artist canvas 3 and the shell 7 out of the inner diameter 86 of the ram frame 85 such that the skirt 11 of the artist canvas 3 contacts the bevel 143 of the crimp die outer frame. That action bends the skirt inwardly inside the frusto-conical wall 15 of the formed back 9. Continued advancement of the ram plug forces the crimp die outer frame against the springs 137, which collapse to push the shell wall 8 over and around the back frusto-conical wall 15.

Final advancement of the ram plug 73 forces the free edge 13 of the shell wall 8, which is covered by the artist canvas 3, against the bevel 143 of the crimp die outer frame 135 and bends the shell wall to create the frusto-conical wall 8A. The artist canvas skirt 11 is tightly tucked between the shell wall 8A and the frusto-conical wall 15 of the back 9.

The handle 45 is then reversed, thereby retracting the ram 59 by means of the spring 69. The completed canvas button 1, with its characteristic frusto-conical wall 8A and tightly tucked skirt 11, is removed from the crimp die 111. The universal assembly machine 33 is then ready to manufacture another canvas button 1.

The round canvas button 18 of FIG. 2 with the collet 20 is manufactured in substantially the same way as the canvas button 1 with the formed back 9. The canvas button 18 has the advantage of being capable of use with a different variety of findings, e.g., mirrors and spring pins, than the canvas button 1.

Round Canvas Button With Flat Back

Turning to FIGS. 11 and 11A, the present invention further includes a round canvas button 161 made with a flat back. A circular piece of artist canvas 3′ overlays a domed shell 7′ in the same manner as the artist canvas 3 of FIGS. 1, 1A, 1B, and 2. Reference numeral 157 indicates a flat back in the form of a disk having a margin 158 that defines a circular periphery 159. The flat back 157 may be made of metal. However, I have found that a flat back made of a hard plastic and having a thickness of approximately 0.04 inches also works very well.

The universal assembly machine 33 is also capable of manufacturing the round canvas buttons 161 with the flat backs 157. The flat back is placed against the shell 7′ in a manner that tucks a skirt 11′ of the artist canvas 3′ between the back periphery 159 and the wail 8A′ of the shell 7′. The shell wall 8A′ is bent around the flat back periphery 159 to form the characteristic frusto-conical wall 8A′ and tucked skirt 11′ on the completed flat back canvas button 161. The center region 160 of the flat back 157 is close to and generally parallel to the shell dome 6′.

To manufacture the round flat back button 161, the only modification required to the machine 33 is a different pedestal for the crimp die. Looking at FIGS. 12A-12C, a crimp die 163 has a crimp die outer frame 135′ and springs 137′ that are the same as the outer frame 135 and springs 137, respectively, of the crimp die 111 described previously. The pedestal 165 of the crimp die 163 has an external shoulder 129′ that is in the same location relative to the die table 97 as the shoulder 129 of the crimp die pedestal 127 of the crimp die 111. However, the pedestal 165 has a top surface 167 that lies in a plane that is at a greater distance from the die table 97 than the top surface 131 of the crimp die pedestal 127. The shoulder 129′ terminates in a pedestal outer diameter 171. There is a step in the pedestal outer diameter 171 opposite the shoulder 129′ so as to form an annular notch 169 adjacent the pedestal top surface 167 and the pedestal outer diameter 171.

The process for manufacturing a round flat back canvas button 161 using the universal assembly machine 33 with the crimp die pedestal 165 is very similar to the process for manufacturing the round canvas button 1 using the crimp die pedestal 127. The process begins by loading a piece of artist canvas 3′ and shell 7′ in the pickup die 109 in the same manner as shown in FIG. 9A. After the pickup stroke, the artist canvas and shell are captured by friction in the ram frame 85 as previously described in connection with FIGS. 9B and 9C.

Looking at FIG. 12A, a round flat back 157 is placed on the top surface 167 of the crimp die pedestal 165. After indexing the machine die table 97 to place the crimp die 163 under the machine ram 59, the handle 45 is pivoted to advance the ram 59 in a crimp stroke. The ram plug 73 pushes the artist canvas 3′ and shell 7′ out of the ram frame 85. Continued advancement of the ram causes the artist canvas skirt 11′ to contact the bevel 143′ of the crimp die ram frame 135′, FIG. 12B. Further ram advancement causes the skirt to bend inwardly on top of the flat back and to tuck between the flat back periphery 159 and the shell wall 8. The free edge 13′ of the shell contacts the crimp die outer frame bevel 143′ and bends inwardly within the notch 169, as shown at reference numeral 8A′. FIG. 12C shows the final working position of ram advance, at which position the round canvas button 161 with the flat back is completed. The shell of the round canvas button 161 has the characteristic frusto-conical wall 8A′ and tightly tucked skirt 11′.

Crimp Die Adapter

The versatility of the universal assembly machine 33 is further exemplified by the fact that the round canvas button 161 with the flat back 157 can be manufactured without substituting the crimp die pedestal 165 for the crimp die pedestal 127. With reference to FIG. 15, the crimp die pedestal 127 used to assemble the canvas button 1 is shown, having the top surface 131 and recess 133. An adapter 173 is used with the pedestal 127 to simulate the crimp die pedestal 165, described previously, used to assemble the canvas button 161. The adapter 173 has a top surface 175, an undercut surface 168, and a pilot 177. When the adapter undercut surface 168 is placed on the pedestal top surface 131 with the adapter pilot 177 inside the pedestal recess 133, the adapter top surface 175 is in the same relative location as the top surface 167 of the pedestal 165, FIGS. 12A-12C. An outer diameter 179 of the adapter is smaller than the outer diameter 130 of the pedestal. There is thus an annular notch 181 surrounding the adapter outer diameter 179 adjacent the adapter top surface 175.

FIG. 15A shows a modified adapter 180 in place in the crimp die 111. The adapter 180 has a bottom surface 182, a top surface 184, an outer cylindrical surface 186, and a second outer cylindrical surface 178. When the adapter bottom surface 182 is placed on the top surface 131 of the crimp die pedestal 127, the adapter top surface 184 is in the same relative location as the top surface 167 of the crimp die pedestal 165, FIGS. 12A-12C. The adapter outer surface 186 is guided by the inner diameter 188 of the crimp die outer frame 135. When the adapter 180 is in place, there is an annular notch 190 between the adapter surface 178 and the inner diameter 188 of the crimp die outer frame 85 adjacent the adapter top surface 184.

By using the adapters 173 or 180, the crimp die pedestal 127, which is used to make the round canvas button 1 as explained with reference to FIGS. 10A-10C, can also be used to make the flat back canvas button 161 as explained with reference to FIGS. 12A-12C. In other words, the crimp die pedestal 127 and adapters 173 or 180 are interchangeable with the crimp die pedestal 165. The adapters 173 and 180 thus contribute greatly to the economy and versatility of the universal assembly machine 33.

Round Canvas Button With A Planar Flange

It is an important feature of the present invention that artist canvas is also incorporated into round canvas buttons 193 having a planar flange as shown in FIGS. 13 and 13A. A circular piece of artist canvas is indicated at reference numeral 185. Reference numeral 189 indicates a domed shell, and reference numeral 191 indicates a flat back. The artist canvas 185, shell 189, and flat back 191 are assembled together to make a round canvas button 193 with a planar flange 199B. The characteristic features of the round canvas button 193 are that the shell flange 199B is parallel to the plane of the back 191, and the outer edge 206 is as thin as the incorporated materials allow.

In its initial condition prior to any transformation performed according to the present invention, the domed shell 189 has an appearance generally similar to the shell 7 of FIG. 1A. That is, the shell 189 has a dome 209 and an annular wall 199 with a free edge 198.

The round canvas button 193 with planar flange 199B is manufactured by using a third press stroke on the machine 33. First, the shell dome 209 is covered with the artist canvas 185. The artist canvas 185 and shell 189 are loaded in the machine pickup die 109 as described previously in conjunction with FIG. 9A. Then a pickup stroke is performed as described previously in connection with FIGS. 9B and 9C. After a round flat back 191 is loaded in the crimp die 163, a crimp stroke is performed as described in conjunction with FIGS. 12A-12C. For the crimp stroke, a crimp die with either the crimp die pedestal 127 with the adapter 173 of FIG. 15 or the adapter 180 of FIG. 15A, or the crimp die pedestal 165 of FIGS. 12A-12C, can be used. It will be recognized that at the end of the crimp stroke, FIG. 12C, a round flat back canvas button 161 of FIG. 11A, has been produced. The round flat back canvas button 161 is produced as an intermediate step in making the canvas button 193 with the planar flange 199B.

The third press stroke is used to complete the manufacture of a canvas button 193 with a planar flange 199B, FIG. 13A. The round flat back button 161 is removed from the crimp die 111 (FIG. 12C) and is loaded back into the pickup die 109, FIG. 14A. The free edge 198 of the shell frusto-conical wall 8A′, covered with the tucked artist canvas 185, rests on the upper surface 117 of the pickup die pedestal 113. The machine die table 97 is indexed to place the pickup die under the ram 59. That action causes the shifter post 103 to contact the finger 91 and rotate the ram frame 85 to the pickup mode whereat the pins 87 are out of alignment with the holes 68 in the carrier 63.

The handle 45 is pivoted in the third press stroke to advance the ram 59, carrier 63, plug 73, and ram frame 85 until the ram frame contacts the pickup die outer frame 119, FIG. 14B. Continued advancement of the ram causes compression of the springs 121 and the tapered surface 81 of the ram plug 73 to contact the front end 202 of the periphery 200 of the flat back button 161. Final ram advancement forces the previously formed frusto-conical wall 8A′ of the shell 189 to press against the surface 117 of the pickup die pedestal 113 and bend inwardly, undergoing compressive forces, tightly against the back 191. At that point, the previous frusto-conical wall 8A′ has bent into the flange 199B that is coplanar and parallel to the back 191, FIGS. 13A and 14C. The artist canvas 185 is tightly tucked at reference numeral 201 around the back periphery 203 and between the shell flange 199B and the back 191. At the end of the third press stroke, the ram 59 is retracted to yield a completed round canvas button 193 with a planar flange 199B.

Rectangular Canvas Button With Coplanar Flanges

A rectangular canvas button 211 with coplanar shell flanges is shown in FIGS. 16-18. The rectangular canvas button 211 has a shell 213, which is preferably made of sheet steel approximately 0.008 to 0.009 inches thick. The shell 213 has four free edges 215 and clipped corners 217. There is a margin 219 of metal along each of the free edges 215. The rectangular canvas button further comprises a rectangular flat back 221 having a periphery 223, and a piece of artist canvas 225. The artist canvas 225 is generally rectangular in shape, but it has four clipped corners 226. Each of the corners 226 preferably has shallow notch 228. For the purpose of this invention, the artist canvas 225 with the clipped corners 226 and notches 228 is considered a rectangular piece of artist canvas. The flat back 221 may be adapted with one or more holes to carry a pin or other finding, as well as a magnet. The rectangular canvas button is characterized by the fact that the shell margins 219 are bent to have flanges 227 that all lie in a single flat plane 229.

The rectangular canvas button 211 with the coplanar shell flanges 227 may be manufactured using a two-stroke manual machine 231, FIGS. 19-27. The machine 231 is comprised of a box framework 233 that includes a base 235, a center column 237, an end column 239, and a crown 241.

Pivotally connected to the crown 241 is a handle 243. In the illustrated construction, the handle 243 has a pair of plates 245 that terminate in a hand grip 247. The plates 245 have respective cam surfaces 249 opposite the grip 247. In FIG. 19, the handle is in a ready position.

Ram

A ram 251 is supported and guided by the crown 241 for reciprocating along a vertical ram axis 253. The ram 251 includes a carrier 255 and a ram die 257. For the particular machine 231 illustrated, the carrier 255 is made with a guide bar 259 and a shifter cage 261. Ram springs 263 act on screws 265 and the crown to bias the ram upwardly against the crown 241.

There are a pair of steps 267 on the opposite ends of the guide bar 259 such that the guide bar has a foot section 269. Projecting oppositely from the carrier guide bar 259 are a pair of rollers 271. The rollers 271 are so located as to be contactable by the cam surfaces 249 of the handle 243 when the handle is pivoted away from the ready position.

The ram die 257 is composed of a plug 273, a frame 275, and a pair of support blocks 277. The ram plug 273 is immovably fastened to the foot section 269 of the guide bar 259. A working surface 279 of the plug has a rectangular peripheral lip 281 with a concave inner surface 283.

The ram frame 275 is free to slide on the plug 273 through a distance D in the directions of the ram axis 253. Sliding in the upward direction is limited by contact by the frame top surface 291 with the shifter cage 261. Sliding in the downward direction is limited by overhangs 287 of the support blocks 277. The ram frame has a bottom surface 289, an inner surface 292, and an outer surface 293. At least one, and preferably two, pins 295 are pressed in the frame top surface 291 and are parallel to the ram axis 253. The pins 295 have a protruding length that is slightly less than the sliding distance D of the ram frame on the plug.

The carrier shifter cage 261 is supported on the ran plug 273 and is free to rotate on it. For that purpose, the carrier shifter cage has a center opening 297 that fits loosely over the guide bar foot section 269. A pair of center lugs 299 in the shifter cage opening 297 loosely straddle the guide bar foot section. One end 301 of the shifter cage is close to the frame end column 239. The other end 303 of the shifter cage has a cutout 305 that straddles the frame center column 237. The shifter cage has holes 307 through it that are at the same distance from the ram axis 253 as the pins 295 in the ram frame 275.

Pickup Die And Crimp Die

Rotatably supported on the framework base 235 is a die table 309. Mounted to the opposite ends of the die table 309 are a pickup die 311 and a crimp die 313. The pickup die 311 comprises a pedestal 315 fastened to the die table. The crimp die pedestal 315 has a flat top surface 317 and an external shoulder 319. An outer frame 321 is slideable over the pedestal. Pickup die springs 323 bias the outer frame 321 such that an internal shoulder 325 normally contacts the pedestal outer external shoulder 319. The outer frame has a recess 327 in the top surface 318, and an internal wall 329.

The crimp die 313 is composed of a crimp die pedestal 331 having a top surface 333. Multiple fasteners hold the crimp die pedestal 331 to the die table 309. The crimp die pedestal has an external shoulder 335. A relief surface 337 is parallel to and spaced from the top surface 333. An outer frame 339 is slideable over the crimp die pedestal. Crimp die springs 341 bias the outer frame 339 such that an internal shoulder 343 thereof contacts the pedestal external shoulder 335. The crimp die outer frame has a top surface 345 with a recess 347. A bevel 349 is between the recess 347 and an inner surface 350. The bevel 349 may be flat, but I prefer a concave scalloped shape as is illustrated. The crimp die further has a number of spring cells 351. Each spring cell 351 has a very stiff spring 353 and a plunger 355.

Actuator

The final major component of the machine 231 is an actuator 357. In the machine with the rectangular ram die 257, pickup die 311, and crimp die 313, the actuator 357 is comprised of a pair of fingers 359 and 361 on the shifter cage 261. The actuator further has a vertical shifter post 363 joined to the die table 309. The shifter post 363 is long enough to reach between the fingers 359 and 361 on the shifter cage 261 when the ram 251 is retracted against the frame crown 241.

Operation

The operation of the machine 231 to manufacture a rectangular flat back canvas button 211 begins by placing a shell 213 on the pickup die pedestal 315. See FIG. 19. A piece of artist canvas 225 is placed on the outer frame recess 327. Then the die table 309 is indexed to position the pickup die 311 under the ram 251. Indexing the die table shifts the ram 251 to the pickup mode. When the ram is in the pickup mode, the holes 307 in the shifter cage 261 are misaligned with the pins 295 in the ram frame 275. See FIG. 24. It will be appreciated, of course, that the operation of the machine 349 would be identical if the pins 295 were in the shifter cage 261 and the holes 307 were in the ram frame 275.

The handle 243 is pivoted in the direction of arrow 365 in a pickup stroke. Doing so causes the cams 249 on the handle plates 245 to push against the ram rollers 271 and advance the ram 251. The carrier 255, plug 273, and ram frame 275 advance together until the frame bottom surface 289 contacts the artist canvas 225 in the pickup die 311. The handle continues to pivot, which causes further advancement of the carrier and the plug, but the springs 323 of the pickup die outer frame 321 resist further advancement of the ram frame. However, the carrier shifter cage 261 bears against the pins 295 in the ram frame, so the force from the handle is transferred to the pickup die outer frame. The force applied to the handle is sufficient to compress the pickup die springs and force the pickup die outer frame downwardly toward the die table 309. That action causes the ram frame bottom surface 289 and inner surface 292 to cooperate and progressively bend the artist canvas 225 over the pickup die pedestal 315. Simultaneously, the ram frame bottom surface and inner surface progressively bend the margins 219 of the shell 213 over the pickup die pedestal, FIG. 23. The artist canvas then has a skirt 367 that overhangs the free edges 215 of the shell.

At the end of the pickup stroke, the handle 243 is pivoted in the reverse direction 369. The ram springs 263 urge the ram 251 upwardly against the frame crown 241. As the ram retracts, the bent artist canvas 225 and shell 213 remain by friction inside the ram frame inner surface 292.

A flat back 221 is placed on the crimp die pedestal 331. The die table 309 is then indexed in the direction of arrow 370, FIGS. 24 and 25. Indexing the die table switches the ram 251 to the crimp mode. In that situation, the holes 307 in the shifter cage 261 are aligned with the pins 295 in the ram frame 275.

The crimp stroke begins as shown in FIG. 25. The handle 243 is pivoted in the direction of arrow 365 to advance the ram 251, together with the artist canvas 225 and shell 213. Ram advancement continues until the bottom surface 289 of the ram frame 275 contacts the recess 347 in the crimp die outer frame 339. See FIG. 26A. Although the handle 243 continues to pivot, the crimp die springs 341 resist any downward motion of the crimp die outer frame 339 and also any further advancement of the ram frame 275. The pins 295 enter the associated clearance holes 307. Consequently, the ram plug 273 is free to slide inside the ram frame, FIG. 26B, until the carrier shifter cage 261 contacts the frame top surface 291. That action pushes the shell 213 and artist canvas 225 most of the way out of the ram frame inner surface 292 and also causes the skirt 367 of the artist canvas to contact the bevel 349 of the crimp die outer frame and bend inwardly on top of the flat back 221.

Advancement of the ram plug 273 continues until the free edges 215 of the shell 213 approach the bevel 349 and become separated from it only by the artist canvas 225. With the plug 273 pushing on the shell and artist canvas, resistance to bending of the metal shell forces that crimp die outer frame 339 downwardly against the resistance of the springs 341. As a result, the shell and artist canvas approach the flat back 221. The artist canvas skirt 367 tucks between the shell margins 219 and the flat back periphery 223. The crimp die outer frame continues to move until the plungers 355 of the spring cells 351 abut the die table 309, FIG. 26C. At that point, the crimp die outer frame bevel and the crimp die pedestal relief surface 337 form a substantially continuous surface.

The combined force of the spring cell springs 353 and the crimp die springs 341 prevents further movement of the crimp die outer frame 339, so continued pivoting of the handle 243 and advancement of the ram plug 273 is not accompanied by any movement of the crimp die outer frame or the ram frame 275. Consequently, the ram plug 273 slides further inside the ram frame and further pushes the shell 213 and artist canvas 225 out of the ram frame. The force applied to the handle is sufficient, because of the scalloped bevel 349, to bend the shell margins 219 into angular flanges 371. The continuous surface between the bevel and the pedestal relief surface 337 guides the shell angular flanges 371 and artist canvas skirt 367 into a notch 373 under the flat back 221 as the ram plug approaches the crimp die pedestal 331. See FIG. 26D.

To complete the manufacture of the rectangular canvas button 211, a final force is applied to the machine handle 243, FIGS. 26E and 27. That final force is transferred through the ram shifter cage 261 to the ram plug 273. The final force is sufficient to compress the springs 353 of the crimp die spring cells 351. The crimp die outer frame 339 slides a short distance in unison with the ram frame and ram plug. The ram-plug working surface 279 and lip 281 force the shell angular flanges 371 to bend against the crimp die pedestal relief surface 337. The shell angular flanges are bent into flanges 227 that are flat and that lie in the single plane 229. The handle 243 is then reverse pivoted, the die table 309 is indexed in direction of arrow 375 (FIG. 20), and the completed rectangular canvas button 211 is removed from the crimp die 313. In that manner, the rectangular canvas button is completely manufactured using only two strokes of the machine 231.

Round Button Machine

Round canvas buttons 193 with the coplanar flange 199B are also manufacturable in a two-stroke process. Turning to FIGS. 28-32, a machine 377 has a box frame 233′ comprised of a base 235′, center column 237′, end column 239′, and crown 241′ that are substantially similar to the corresponding components of the machine 231 of FIGS. 19-27. The machine 377 further has a handle 243′ that pivots in the crown 241′ to advance a ram 379 along a ram axis 253′. A die table 309′ is indexible about the frame center column 237′ to position either a pickup die 402 or a crimp die 411 under the ram 379.

The ram 379 is composed of a carrier 385 with rollers 387 that are contactable by cams 249′ on the handle 243′. The carrier 385 has a pair of holes 307′. The ram 379 further comprises a cylindrical plug 389 fastened to the carrier 385. The plug 389 has a working surface 279′ with a circular lip 281′ having a concave surface 283′. The plug has an external shoulder 391.

Slideable and rotatable over the ram plug 389 is a ram frame 393. Sliding of the ram frame 393 in the downward direction is limited by an internal shoulder 395 that contacts the plug external shoulder 391. A pair of pins 295′ are pressed in the frame top surface. The pins 295′ are at the same distance from the ram axis 253′ as the holes 307′ in the carrier 385.

The machine 377 further comprises an actuator 397 that includes a shifter post 363′ upstanding from the die table 309′. The actuator 397 also includes a pair of fingers 398 and 400 that jut from the ram frame 393. Indexing the die table 309′ causes the shifter post 363′ to travel in an arc about the frame center column 237′ and contact one or other of the fingers 398 and 400.

Pickup Die And Crimp Die

A pickup die 402 of the machine 377 is comprised of a pickup die pedestal 399 fastened to the die table 309′. An outer frame 401 is slideable over the pickup die pedestal 399. Pickup die springs 403 bias the outer frame 401 against an external shoulder 405 on the pickup die pedestal. There is a recess 407 in the pickup die outer frame top surface 409.

A crimp die 411 has a crimp die pedestal 413 with a top surface 415, and an external shoulder 417. A crimp die outer frame 419 is biased by crimp die springs 421 such that an internal shoulder 423 contacts the crimp die pedestal external shoulder 417. The crimp die outer frame 419 has a recess 425 and a bevel 427. The crimp die outer frame further has a number of spring cells 351′, each with a stiff spring 353′ and a plunger 355′.

Operation

The operation of the machine 377 to manufacture round canvas buttons 193 is very similar to the operation of the machine 231 for manufacturing rectangular canvas buttons 211. A shell 189 is placed on the pickup die pedestal 399, and an artist canvas 185 is placed in the recess 407 of the pickup die outer frame 401. The die table 309′ is indexed to position the pickup die 402 under the ram 379. Indexing the die table 309′ causes the shifter post 363′ to contact the finger 400 and rotate the ram frame 393 on the plug 389. When that occurs, the pins 295′ become misaligned with the clearance holes 307′ in the carrier 385, FIG. 31.

The handle 243′ is pivoted in a pickup stroke to advance the ram 379. The ram advances until the frame bottom surface 429 contacts the artist canvas 185 in the pickup die 402. The springs 403 of the pickup die outer frame 401 resist further advancement of the ram frame 393. However, the carrier 385 bears against the pins 295′ in the ram frame, so the force from the handle is transferred to the pickup die outer frame 401. The force applied to the handle is sufficient to compress the pickup die springs and force the pickup die outer frame downwardly toward the die table 309′. That action causes the ram frame bottom surface 429 and inner surface 431 to progressively bend the artist canvas 185 over the shell 189. A wrinkled skirt overhangs the shell free edge 189.

At the end of the pickup stroke, the handle 243′ is pivoted in the reverse direction. As the ram retracts, the artist canvas 185 and shell 189 remain by friction inside the ram frame inner surface 431.

A flat back 191 is placed on the crimp die pedestal 413. The die table 309′ is then indexed to position the crimp die 411 under the ram 379. See FIG. 28. Indexing the die table to position the crimp die under the ram switches the ram to the crimp mode. That is achieved by the arcuate travel of the actuator shifter post 363′ to contact the finger 398 on the ram frame 393 and rotate the frame to the position shown in FIGS. 28 and 29. In that situation, the holes 307′ in the carrier are aligned with the pins 295′ in the ram frame.

The handle 243′ is pivoted in a crimp stroke to advance the ram 379, together with the artist canvas 185 and shell 189, until the bottom surface 429 of the ram frame 393 contacts the recess 425 in the crimp die outer frame 419. The operation of the machine 377 during the crimp stroke is substantially identical to the operation of the machine 231 that manufactures the rectangular canvas button 211 as was described previously in connection with FIGS. 26A-26D. At the end of the crimp stroke, the round canvas button 193 with the coplanar flange 199B has been completed by the two-stroke process of the machine 377.

In summary, the results and advantages of artist canvas can now be more fully realized. The canvas buttons of the invention provide both a sturdy mounting for the artist canvas, as well as a convenient way to display unique and custom produced paintings. This desirable result comes from using the combined functions of the artist canvas, shells, and backs. A round canvas button may have a formed back or a flat back; the universal assembly machine 33 is equally capable of manufacturing both. The present invention further includes round and rectangular canvas buttons with coplanar flanges. The rectangular canvas button 211 with coplanar flanges 227 is manufacturable using only two strokes of the machine 231. The round canvas button 193 with the coplanar flange 199B may be manufactured either by using the two strokes of the machine 377 or by using the third-press stroke of the machine 33.

It will also be recognized that in addition to the superior performance of the canvas buttons, their constructions are such as to cost little, if any, more than traditional buttons. In fact, the versatility of the machines 33, 231, and 377 enable both the round and rectangular canvas buttons to be efficiently manufactured at high production rates.

Thus it is apparent that there has been provided, in accordance with the invention, two-piece round and rectangular canvas buttons that fully satisfy the aims and advantages set forth above. While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to-embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. 

1. canvas button for fine art painting comprising: a. a shell having a free edge and a margin adjacent the free edge; b. a back having a periphery and a margin adjacent the periphery; and c. a piece of artist canvas overlying the shell and tightly tucked between the shell margin and the back margin, so that the shell provides a support for painting on the artist canvas, wherein the shell, back, and artist canvas are substantially round to thereby present a round artist canvas medium for receiving a selected color pattern; and d. wherein the back is a flat back; and e. the shell margin comprises a flange that is substantially parallel to the flat back and that lies in a single plane; and f. the artist canvas is tightly tucked between the shell flange and the flat back margin.
 2. The canvas button of claim 1 wherein the shell, back, and artist canvas are substantially rectangular in shape, so that the canvas button presents a substantially rectangular surface of artist canvas that is paintable by an artist.
 3. the canvas button of claim 2 wherein: a. the back is a flat back; b the shell margin is in the shape of multiple flanges that are substantially parallel to the flat back and that lie in a single plane; and c. the artist canvas is tightly tucked between the shell flanges and the flat back margin.
 4. A canvas button comprising: a. a back having a margin that defines a periphery; b. a shell having a center region, a free edge, and a margin between the center region and the free edge; and c. a piece of artist canvas overlying the shell and having a skirt that overhangs the shell free edge, the skirt being tightly tucked between the shell margin and the back periphery to enable an artist to paint on the artist canvas and to display a resulting painting without removal of the artist canvas from the back or shell; and d. wherein the back margin comprises a first frusto-conical wall; and e. the shell margin comprising a second frusto-conical wall parallel and closely spaced to the back margin first frusto-conical wall; and f. wherein the artist canvas skirt is tightly tucked between the first and second frusto-conical walls; and g. wherein the back has a center region that is generally parallel to and closely spaced to the shell center region; and h. wherein the back is a flat disk; i. wherein the shell margin comprises a frusto-conical wall that is closely spaced to the back periphery; and j. wherein the artist canvas skirt is tightly tucked between the shell frusto-conical wall and the back periphery; k. wherein the back margin is substantially flat; l. wherein the shell margin lies in a plane that is parallel to and closely spaced to the back margin; and m. wherein the artist canvas is tightly tucked between the shell margin and the back margin.
 5. In combination: a. a shell having a center region, a free edge, and a margin between the center region and the free edge; b. a piece of artist canvas overlying the shell center region and margin and having a skirt that overhangs the shell free edge; and c. a back defining a periphery that cooperates with the shell margin to tightly tuck the artist canvas skirt therebetween, so that the shell provides a sturdy mounting for the artist canvas; d. wherein the shell margin comprises a frusto-conical wall; and e. wherein the back is substantially flat.
 6. The combination of claim 4 wherein at least a portion of the shell margin comprises a flange that lies in a flat plane that generally parallel to the flat back.
 7. An assembled medium for displaying a selected color pattern comprising: a. a shell with a dome, and a wall surrounding the dome; b. a back having a circular periphery and a margin adjacent the periphery; and c. a piece of artist canvas overlying the shell dome and wall arid tightly tucked between the shell wall and the back periphery, so that the artist canvas presents a medium, and the shell provides a support, for displaying a selected color pattern on the artist canvas; and d. the back margin comprises a frusto-conical wall; and e. the shell wall is frusto-conical and surrounds the back frusto-conical wall, and the artist canvas is tightly tucked between the shell and back frusto-conical walls; and wherein the back is a flat disk. 